A method of heating a package of food

ABSTRACT

The method provides for heating a food package by boiling wherein between the lid and the tray a liquid-tight mechanical connection is provided, plus a gas-tight meltable seal. In heating under water the seal melts and allows the escape of steam from the interior while the mechanical connection maintains the interior free of indrawn water.

United States Patent 1 Bemiss 1451 Feb. 13,1973

[54] A METHOD OF HEATING A PACKAGE OF FOOD 75 Inventor: Robert' P.Bemiss, Hillsborough,

.Calif.

[73] Assignee: RobolexJ nc.

[58] Field 1 se r .2'29/; 1)1o.- 14; 99/171 171 c,99/171H,1,171-R,174,185,214

[56] References Cited UNITED STATES PATENTS 2,633,284 3/1953 Moffett etal. ..99/171 H X 2,844,475 7/1958 Barnes et a]. ..99/171 H X 3,468,4719/1969 Linder ..229 010. 14

2,986,319 5 1961 Bierman et aL. ...229/D1G. 14 1 3,027,261 3 1962 Samara..99/171 1-1 FOREIGN PATENTS OR APPLICATIONS 49 ,737 10 1953 v Canada.Q.=99/171 1! Primary Examiner-Frank W. Lutter Assistant Examiner-StevenL. Weinstein AttorneyAllen & Chromy [57] ABSTRACT The method providesfor heating a food package by boiling wherein between the lid and thetray a liquidtight mechanical connection is provided, plus a gastightmeltable seal. in heating under. water the seal melts and allows theescape of steam from the interior while the mechanical connectionmaintains'the interior free of indrawn water. 2

1 Claim, 18=Drawing Figures Tres sler ..99 1711-1 x Fl 6 2 INVENTOR.

ROBERT P. BEMISS ATTORNEYS PATENTEDFEBI 3l973 3,716,370

' SHEET 3 or s INVENTOR. ROBERT P. BEMISS ATTORNEYS PATENTEBFEBI 31973,370

SHEET 0F 5 FIG. l3

INVENTOR. ROBERT P. BEMISS ATTORNEYS METHOD OF HEATING A PACKAGE OF FOODDESCRIPTION OF THE INVENTION This application is a division of mycopending Application Ser. No. 844,494 filed Jul. 24, 1969 forPACKAGING, now US. Pat. No. 3,580,478.

The present invention relates to methods of making packages fromcartons, and is concerned more particularly with the provision of acarton or package of a traylike body and a lid for a tray or otherreceptacle having horizontal flange means at its open end to which thelid is applied. The lid is held in place by a mechanical connection, andif desired, a caulk or hot melt seal is employed.

It is a general object of the invention to provide an improved method ofheating a plastic package by boiling wherein provision is made forescape of any steam generated from the boiling of the contents of thepackage.

Another object of the invention is to provide a method of heating foodin a carton which incorporates heating a package by boiling in waterwhich'package incorporates a seal preventing the entry of water into thepackage.

Other objects and advantages of the invention will be apparent from thefollowing description of certain preferred embodiments thereof asillustrated in the accompanying drawings in which:

FIG. 1 is a perspective view of a closed package;

. FIG. 2 is a plan view of a blank for the lid of a package;

FIGS. 3, 4 and 5 illustrate manufacturing operations performed inconverting the lid blank shown in FIG. 2 to a box-like shape lid asapplied to the package;

FIG. 6 is a view of the lid with the flanges of the tray held by thetrapping walls of the lid;

FIGS. 7 and 8 illustrate one way of effecting the assembly of the lidand the tray by placing the lid in a jig formed as a receptacle andforcing the lid over the tray;

FIGS. 9, and 11 illustrate a modified form of the invention;

FIG. 9 is a perspective view similar to FIG. 1;

FIG. 10 is a fragmentary planview of the blank for forming the lid shownin FIG. 9;

FIG. 11 is a fragmentary sectional view through the assembled package,the lid being shown as applied to the tray with its trapping walls orelements engaged underneath the tray flange;

FIGS. 12 through 18 relate to a further modified form of the invention;

FIG. 12 is the plan view of a package or carton or tray closed with thelid according to the invention;

FIG. 13 is a plan view of the lid blank used in forming the package; 4

FIG. 14 is a plan viewof the lid as applied to a tray ready for closing;and

FIGS. 15 through 18 are enlarged detailed sectional views illustratingthe sequence of the closing opera-v tions.

Referring to FIG. 1, the invention is illustrated in connection with aconventional tray 10 which may be of polyethylene, for example, and of arigid or semirigid construction. This tray hasa flange 11 (FIG. 6)extending around the four sides thereof and being adapted to be fastenedin and trapped by a lid 12 which is of open boxtop construction.

Preferably, the lid 12 may be heat sealed to the flanges 11 by means ofa heat sealing coating 13 as shown in FIG. 6, this coating beingmeltable at or below the temperature of boiling water and preferablybelow this temperature and being an Alathon petroleum and wax formulaproduced by the Continental Oil Company of Ponca City, Oklahoma undertheir Formula No. PPDX l22, as disclosed in the copending and commonlyassigned application of Bemiss and Donald Ser. No. .4I,92l, filed Junel,l970 for SELF-OPEN- ING PACKAGES. Also, the heat sealing of theportions of the lid together and the lid to the flange may beaccomplished where the lid is of paperboard for example, and is coatedwith a polyethylene coating so that the polyethylene tray and thepolyethylene coating can be heat sealed together in usual fashion. Thepackage may be opened in either case by means of a tear strip 15.

Referring again to FIGS. 1 and 6, it is seen that the lid 12 has a topwall 16 surrounded by four side walls 17 and 17a, each of which is bentback upon itself through 180 to provide a bottom portion 18 which isheat sealed at shaded areas 19. The paperboard employed to make the lidmay have a polyethylene coating thereon. The flange portion 18 which isbent through 180 has a spring-like locking or trapping portion extendingupwardly whose upper portion is formed at a double wall by the 180folding of the outer edge portion 22, this being heat sealed to theupper portion of the wall 21 at 23. It will be seen that the upper edgeof the double wall 22 is spaced a little below the upper wall 16 of thelid to provide space for the flange 11, and that the side walls 17 areoutwardly flared for an angle A of about 2 to 4 to provide an entranceopening for the flange and to permit passage of the flange past thedouble wall portion 22 into its trapping or locking position shown inFIG. 6.

The blank for the lid 12 as shown in FIG. 2 includes a central wall 16which is connected by scored or perforated pairs of hinge lines 26 and26a to side wall portions 17 and 17 a The side wall portions 17 and 17aare connected at the outer edge by pairs of perforated hinge lines 27and 27a to respective side flaps 18 and 18a The pairs of side flaps 18and 18a are connected by respective pairs of fully perforated hingelines 28 and 28a to respective flap extensions 22 and 220.

To enable closing of the corners of the lid, a pair of connecting flaps31 (FIG. 2) are provided at each end of the wall portions or flapportions 17a as shown in FIG. 2, being separated by a cut line from theadjacent end portion of the wall or flap portion 17 and being hinged at32 to the adjacent wall portion 17a It will be noted in FIG. 2 that theflap extensions 22 and 22are cut short so they will not interfere withthe location of the connecting flap or tab 31 in the assembly of thelid.

In the operation of assembling the lid, FIG. 3 illus- V trates the flapextensions 22, 22a folded over and heatsealed to the outer edge of theflaps 18, 18a After this operation is performed, as illustrated in FIG.4, flaps l8 and 18a are folded 180 about the hinge lines 27 and 27a tothe positions shown in FIGS. 4 so that a heat sealing operation isperformed at the outer portion of these side walls of the lid 12.Subsequently, these side flap portions are folded for about the hingelines 26 and 26a at thesame time that the connecting tab 31 is insertedinto and seats in the un-heat sealed portion.

. into which the lid 12 can be inserted for assembly, and

then the tray 10 is pressed in inside of the lid, its flange 11 bendingslightly as it passes by slightly the locking or trapping members of thelid and then snapping into place, as seen in FIG. 8, the trappingmembers coming out under the horizontal flanges of the tray to hold itin place in the lid. This operation, of course, is performed after thetray has had the objects to be carried such as frozen food, for example,placed therein.

Afterwards, the tray with the lid thereon would be passed through asuitable heat sealing apparatus of the type disclosed in the U. S. Pat.to Bemiss and Hansen, No. 3,325 ,969. A hermetically sealed package isavailable for use in connection with a product contained therein.

This would be a food product which is subject to being heated or boiledfor serving. The tray is preferably of polyethylene plastic and theproducts therein can be boiled to the desired temperature, the boilingraising the plastic sealant 13 to a temperature above its melting pointso that the heat seal is lost providing an effective one-way valveconstruction entirely around the lid and the tray so that steam or othervapors can escape while no water will be admitted.

The modification shown in FIGS. 9, l and 11 is similar to themodification previously described in many respects and the identicalportions will not be repeated in the description. For example, thisforms employs a polyethylene tray a and a lid 12a It also has the sidewalls or locking portions which are different in construction from thatpreviously described, and the method of fastening the four side flangeso'r flaps of the lid together is also different. Referring to FIG. 10,for example, the lid 12a comprises a central wall 41, which has attachedat its respective sides similar opposite sets of flaps as previouslydescribed and shown in FIG. 2. In this form, the flaps are of slightlydifferent construction, the adjacent flap portion 42 being connected byfold line 43 to the center panel or wall 41 of the lid, and at the toppanel 42a is connected by a perforated hinge line 43a Secured to theouter edge of the flap portion 42 by fully perforated hinge line 44 isan outer or locking flap 46 at the side and 46a at the top. Aconventional corner lock of the type manufactured by the Klik-LokCorporation is provided for securing the ends of the respective flapportions 42 and 42a and 46 and 46a together and this constructionproviding a locking tab Slat each end of the flap portions 42a, tocorrespond to a cutout 52 in the adjacent flap portion 42, the tab 51being adapted to be inserted through the eutout 52 during erectionoperation. Similarly, the tab 53 beyond the cut 52 at each end of theflap portion 42 is adapted to be folded inside of the tab 51 which thenwill be folded and be tucked into the cut slot 52 simultaneously. Theouter trapping portions 46 of the respective edges of the lid haverespective tabs 54 which are cut at 54b form the adjacent wall portionof the wall 46 and has a hinge line 54a at its bottom. A tab 56 isformed at the end of the wall 46a and has a bend line 56a by which it isattached, this provides interlocking construction of these outerportions whereby the locking tab 56 can be bent about its hinge line 56aand inserted through the cut slot 54 b adjacent to the locking tab 54.

With the construction shown in FIGS. 9, l0 and 11, after the lid hasbeen formed, the trapping walls 46 and 46a have a central bulge wherethey are spaced from the adjacent flange walls 42 and 42a and provide aspring portion for snapping underneath the flange ll of the adjacentside of the tray 10a as shown in FIG. 11. This modification of FIGS. 9,10 and 11 does not require any heat scaling in the manufacture of thelid.

Referring to FIGS. 12 through 18, a form of the invention is shown whichis particularly adaptable to producing a boilable package. The tray 10bhas the usual side flanges as 11b and has associated therewith a closurelid 12b The lid 12b is of paperboard and has a plastic coating 61thereon which may be of polyethylene, for example, to match the materialfrom which the tray 10b is made, and to be heat-scalable thereto. Thelid 12b has at its edges respective side flaps 62 and 62a and 63 and and63a, all connected by a scored line 64 to respective pairs of sideextensions to body portion of the lid 12b The side flap portions as seenin FIGS. 15 through 18 can be bent back through 180 so that the sealingcan be effected above the flange 11b at 65, at the U-shaped double wallportion 66, and also underneath the flange 1 lb at 67. The heatsealeddouble wall portion 66 forms a support for the extension edge 67. Withinthe space formed by the bent over portions 62, there is provided alength of caulking or hot melt adhesive 68 which will melt below 212 F,say at l70l so as to effectively vent the package to permit the escapeof steam, particularly at the corners, where the side flap portions 62and 63 would abut each other, but are not overlapped during the heatsealing operation.

Referring to FIG. 12, it will be seen that after heat sealing of thelid, there are four one-way valves 70 where the ends of the flapextension or side flaps 63 and 63a abut the long edges of the side flaps62 and 62a There is no provision for overlapping during heat sealing,but a watertight connection is provided at the lines 70. However steamunder pressure generated during heating of the food product in theclosed package will cause escape of steam at the four corners.

It will be noted that in each of the modifications of FIGS. 1, etc. andFIG. 12 a mechanical securing or mechanical closing of the package isprovided, in the FIG. 1 modification by the trapping construction of thelid and the FIG. 12 modification by the heat seal and overlap of the lidaround the flange. It will be seen that in addition to this mechanicalconnection or attachment that a positive water-tight seal is provided bymeans of the special heat sealing layer 13 as seen in FIG. 6 and bymeans of a bead of hot melt 68 (FIG. 15).

Also, a tear strip 71 is provided, having a handle portion 72 formedfrom the flap portion 630 to enable ready opening of the package when itis required for use. These tear strips are conventional shape andconstruction and similar to the tear strips provided in the previousmodifications.

between said lid and said tray about substantially the entireperipheries thereof which is water-proof in character thereby forming apackage, providing a meltable seal for said mechanical connection aboutsubstantially the entire mechanical connection which is of gas-tightcharacter, heating the package in said liquid to cause melting of thegas-tight seal between the tray and the lid while retaining themechanical connection therebetween, and passing the steam from thecontents of the package to the outside while barring entry of liquidinto the package.

